Data retrieval and coupling system



1l Sheets-Sheet l G. W. HERNAN ETAL DATA RETRIEVAL AND COUPLING SYSTEM Oct. 25, 1966 Filed Nov. 1961 wGm @Si m A mi @IT INVENTORS Ez-nREE-"WI HERNEN ,e STHNLEY H. HUNKINS Ff u@ IfPA/fl/J G. w. HERNAN ETAL 3,281,788

DATA RETRIEVAL AND couPLING SYSTEM l1 Sheets-Sheet 2 Oct. 25, 1966 Filed Nov. 5, 1961 Sx I Oct. 25, 1966 G. W. HERNAN ETAL 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM 1l Sheets-Sheet 5 Filed Nov. .3, 1961 0d 25, 1966 G. w. HERNAN ETAI. 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM Filed Nov. 5, 1961 11 Sheets-Sheet 4 INVENTORS BEREI- W. HERNAN S'IHNLEY H. Hmmms awww@ S n vx Wx x N m N m w N T E K "x www \r www XN @uw NNN Mwmwlk www@ www@ n kxmla m m m f PQ n n Q QU 3km wukoml m mmnzH m RS wvmml Q s l\ #fin u m N 1 .H AM m UQ H\ m m m n W H NNN ww. L n wx m m www uw E 1 unl ES 5^ l... W NN @Q v/ S Q m mul MM 3 um k .ml h L uNuS Q Gm \M\ \m VN QM i u Mm x w N i @www Rm Q www; St llml mb. Q ..k\ n Q Q m @A A QKN ||L A w -MIWH w n In 1 ml @I .www EQ m m Mkml RM mNuQ w. Q nk N m J |L fkk #www ww v w m w x. MMS l m1 J m 31 T Oct. 25, 1966 G. w. HERNAN ETAL 3,231,738

DATA RETRIEVAL AND COUPLING SYSTEM ll Sheets-Sheet 6 Filed Nov. 5, 1961 Oct. 25, 1966 G. W. HERNAN ETAL 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM Filed Nov. 5, 1961 1l Sheets-Sheet 7 Oct. 25, 1966 C;` W HERNAN ETAL 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM Filed Nov. 5, 1961 1l Sheets-Sheet 8 w l T o J j; l M, wf *I4 m' M, f" M 61/ I L M@ d da M4 T 0 FE /F E ,ai 5?*22 Paola 7' if! l l l INVENTORS BEDRETE W HERNHN STHNLEY H. HUMKLNS lffdlli Oct. 25, 1966 G. w. HERNAN ETAL 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM 1l Sheets-Sheet l0 Filed Nov` 3, 1961 Oct. 25, 1966 s. w. HERNAN ETAI. 3,281,788

DATA RETRIEVAL AND COUPLING SYSTEM 11 Sheets-Sheet 11 Filed Nov. 5, 1961 N --.e ms

United States Patent O 3,281,788 DATA RETRIEVAL AND CUPLING SYSTEM George W. Hernan, Haddonfield, and Stanley H. Hunkins,

Merchantville, NJ., assignors to Ultronic Systems Corporation Filed Nov. 3, 1961, Ser. No. 149,913 18 Claims. (Cl. 340-152) This invention relates to data storage and retrieval systems and particularly to a system for retrieving information about stock transactions from a data storage system and supplying the information to a large number of information requesting units.

In the copending patent application of Sinn and Hernan, Ser. No. 113,689, filed May 31, 1961 entitled Data Retrieval System, which application has now been abandoned and continuing `application Serial No. 484,784, filed August 20, 1965, a data storage and `retrieval system is described in which digital stock transaction information is stored on a magnetic drum. A number of information requesting units or consoles are associated with `this equipment and may be located in a stock brokers office or the like. A plurality of such consoles are connected via a terminal switching unit and a communications system to a data retriever unit and, thereby, to the data storage. The requested information is obtained from storage by the data retriever un-it and transmitted back via the terminal switching unit yto the requesting console. In this manner, a large number of consoles may obtain .access to the data storage unit for the desired information. A plurality of such arrangements may be coupled to the memory so that lpluralities of consoles in different remote locations may be serviced by the same data storage unit. In addition, a plurality of consoles more closely positioned to the data storage system may obtain access to the data storage in a similar fashion by means of an output logic unit also connected to the data storage unit. With this system, the information `requested by the operator of any one console is made available to it almost immediately `upon selection of the desired stock and category of information. Thereby, a large number of console operators may gain access `to the central storage system substantially simultaneously and from remote locations.

It is 'an object of this invention to provide a new and improved data retrieval and storage system.

Another object is to provide a new and improved data retrieval and storage system for supplying current information about stock transactions.

Another object is to provide a new and improved data retrieval system in which a large number of requesting units may be connected to a data storage to obtain information therefrom and in which these requesting units may be connected to and disconnected from the system without affecting the operation thereof.

The foregoing and other objects of this invention, the features thereof, as well as the invention itself, may be more fully understood from the following description when read together in connection with the accompanying drawing, Iin which:

FIG. 1 is a schematic block diagram of an information storage and retrieval system embodying this invention;

FIGS. 2A, B, and C are schematic block and logic diagrams of portions of a data collector unit that may be used in connection with the system of FIG. 1;

FIGS. 3A and 3B are schematic block `and logic diagrams of portions of a data terminus unit that may be used in connection with the system of FIG. l;

FIG. 4 is a schematic block and logic diagram of a retriever unit that may be used in connection with the system of FIG. 1;

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FIG. 5 is a schematic block and logic diagram of a slave output unit that may be used in the system of FIG. 1;

FIG. 6 is a schematic circuit diagram of a logical unit that may be used in the schematic block diagrams of FIGS. 1-5;

FIG. 7 is a schematic cir-cuit diagram of another form of logical unit that may be used in the block diagrams of FIGS. 1-5;

FIG. 8 is a schematic circuit diagram of a ilip-op unit that may be `used in the block diagrams of FIGS. 1-5;

FIG. 9 is a schematic diagram showing the arrangement of information on a magnetic drum in the diagrams of FIGS. 1 and 2;

FIG. 10 is a schematic graphical diagram showing the time relations of waveforms occurring in `the system;

FIG. 11 is a schematic block and logic diagram of a modification of the slave unit of FIG. 5;

FIGS. 12A and 12B, taken together, are schematic block and logic diagrams of a modified form of the data collector of FIGS. 2B and C; and

FIG. 13 is a Vschematic circuit diagram of a portion of a console display system for use with the data collector of FIG. 12.

In the drawing corresponding parts are referenced by similar numerals throughout.

General system In FIG. 1 a storage drum memory 20 receives information from a source 22 via a loading system, and control 24 via read-write recording heads and amplifiers 26, 28, and 31) respectively associated with storage bins 32, 34, 36 on the `recording drum 20, which bins 32, 34, and 36 store information related to the stock identification code (SIC) and associated High and Low stock transaction prices. Other bins on the drum 20 may be used to store associated information such as Last price, Closing price, Volume of sales, Number of transactions, Time of transaction, Stock earnings, and Bid and Ask prices. A suitable loading system of `this sort is described in the copending application of Sinn, Information Storage System, Ser. No. 108,120, filed May 5, 1961.

Connected to the read-Write recording heads and arnplifiers 26, 28, and 30 are a plurality of slave output units 38 and 40; additional such output units may be provided. The first slave output 38 is connected to four retriever units 42, 44 which, in turn, are connected to receiver-transmitter communication units 45, 46. The receiver (Rx) 45 and transmitter (Tx) 46 are respectively connected via communication lines to a Tx l47 and Rx 48 which, in turn, are connected to a data terminus unit 50. The data terminus `unit 50, in turn, is connected to a series of data collector (DC) units 52 and 54, eight of which are shown connected in series. Connected yto each data collector 52 and 54 (in the ilustrated form of the invention) are up to eight console units 56, 58 and 60, 62; #l to #8 consoles 56, 58 are connected to DC-l, `and #57 to #64 consoles `60 and 62 are connected to DC-8. This invention is not limited to any particular number of slave output, retriever, terminus, collector, or console yunits in the system; and a lesser or greater number may be incorporated to meet various requirements.

Signal transmission through this system is generally by way of binary signals in the form of high and low voltage levels respectively representing the binary digits 0" `and 1. The communication system 45-48 may be of 'any suitable type employing such signals or any other appropriate `form of signals and especially adapted for long distance transmission; an appropriate form of this system which is commercially available is a dataphone communication system for transmitting digital information via a telephone line using a frequency modulation system. For example, signals of two different frequencies are generated and transmitted in response to the different voltage levels which represent the binary digits and 1. The Tx units 46, 47 convert the digital voltage levels from the retriever 42 and data terminus 50 to signals of the two different frequencies, and the Rx units 45, 48 recouvert the transmitted signals back to the appropriate voltage levels. Each of the other retriever units represented by the unit 44 is similarly connected via transmission and receiver units to a data terminus and, via data collectors, to pluralities of console units in a similar fashion.

In operation, the console units S662 are successively connected via the data collectors 52, 54 to the data terminus 50 to supply a request for stock transaction information relevant to a certain stock. Each console un-it supplies a stock identifier code SIC and also identifies the particular category of transaction information desired. The signals representing this request are transmitted via the data terminus and Tx 47 to Rx 45 and to the #l retriever 42. The latter unit 42, in turn, transmits this information to a slave output 38 which obtains access to an appropriate part of the drum 20 in which the SIC and requested information category are stored. This information is obtained by the slave output 38 and transmitted back via retriever 42, Tx 46, Rx 48 to the data terminus 50 which, in turn, supplies the reply message via one or more of the data collectors to the requesting console.

A plurality of slave outputs similar to the unit 38 may be connected to the drum storage 20 via the read-write heads and amplifiers 26-30; each such slave output would be connected independently via similar retriever, communication, data terminus, and data collector units to the consoles, and the operation is similar to that described above.

In addition, a slave output 40 connected to the recording heads and amplifiers 26-30 is directly connected to a series of data collectors 64, 66, and 68 which, in turn, are connected to pluralities of eight consoles 70, 72, 74, etc. In operation, any one of the consoles 70 and 72, connected to the data collectors 64-68, may obtain access via the slave output 40 to the requested portion of the drum storage 20 to obtain the desired information in a manner similar to that described above. The consoles 70, 72, and 74 may be connected relatively close to the storage unit 20 so that the coupling system of a retrieve-r, communication units, and a data terminus are not required. The slave outputs 38 and 40 are generally the same in construction and may have connected thereto an appropriate combination of retrievers or, alternatively, the data collectors dire-ctly.

The source 22 of the information may contain a master unit including 'a magnetic drum, similar to the drum 20, which is kept in updated condition. The master unit of the source 22 `is used to maintain updated the slave memory 20 and any other slave memories (not shown) by means of loading systems 24.

System logic and circuits The system logic described hereinafter is based on NOR logic. A suitable form of NOR circuit that may be used is shown in FIG. 6. Three input terminals 600 are connected via separate diodes 602 and a parallel combination of resistor 604 and capacitor 605 to the base of a transistor 606 connected in the common-emitter mode. Resistors 608 and 610 on either side of the resistor 604 form a voltage divider network which tends to forward bias the base-emitter path of transistor 606. A collector resistor 610 and a clamping diode 612 form the output circuit of the transistor, the output being taken at the collector of the transistor with the diode 612 determining the output voltage when the transistor is not conducting.

In operation, the input voltages applied to the terminals 600 are either ground potential or -V2, which respectively represent the binary digits 1 and 0. If any one of the input terminals 600 is at ground potential, the transistor 606 is biased off, and the output collector voltage is V2. Thus, the circuit oif transistor 606 functions to logically invert the input signal. If all of the input terminals 600 are at -V2, the diodes 602 decouple these inputs from the transistor base, and the voltage divider network 608, 604, 610 function to render the transistor 606 conductive. The output voltage is substantially ground potential when the transistor 606 conducts due to the small voltage drop in the emitter collector path. Thus, the NOR circuit operates as an and gate and inverter for low violtage signals and as a buffer and inverter for high voltage signals.

`In FIG. 7 a modified form of the NOR circuit of FIG. 6 is shown, and corresponding parts are referenced by similar numerals. In this circuit an additional input terminal 614 is connected directly to the base of the transistor 606. The operation of the circuit with the input signals applied to the terminals 600 is generally the same; however, a ground input signal at terminal 614 (generally applied via a diode, not shown or via a pulse steering gate 618, described below) overrides the effect of the other inputs and controls the state of the transistor 606. When any of the inputs of the circuits of FIGS. 6 and 7 are open-circuited or at a floating voltage momentarily, they are effectively disconnected.

The circuits of FIGS. 6 and 7 are cascaded in logical nets with the output terminal of one NOR circuit being connected to the input terminal of a succeeding NOR circuit. These circuits are used with different numbers of inputs, and with a single input they function as inverter amplifiers. The symbols for these circuits used in the logic diagrams are shown in the figures. Where a plus symbol is added to the symbol, the effective logic operation is that of OR, but the circuit lis unchanged. Where these circuits are used to drive a large load, a plurality thereof may be connected in parallel.

In FIG. 8 a fiip-op circuit is shown that is formed by two NOR circuits of the type shown in FIG. 7 connected in a regenerative configuration. Parts of one of the transistor circuits are referenced by the same numerals as in FIG. 7, and those of the other circuit are referenced by the same numerals with the addition of a prime The circuit of transistor 606 is referenced as the l-side of the flip-flop, and the circuit of transistor 606' is represented as the O-side of the flip-flop. The collector of transistor 606 is connected via diode 602 to the base of transistor 606', and the collector output of transistor 606' is connected via the input diode 602 to the base of transistor 606. The circuit operates as a bistable multivibrator so that when one transistor is turned off, the other transistor is turned on, and vice-versa.

In addition to the circuit elements described thus far for the flip-flop of FIG. 8, a reset input terminal 616 is connected via diode 618 to tht junction of diode 602 and resistor 604. Thus, when a ground level reset signal is applied to the terminal 616, the l-transistor 606 is turned off, and the O-transistor 606 is turned on. In the reset condition, the output voltages are low at the l-output terminal and high at the O-output terminal. In the set condition of the flip-flop, the opposite output voltage conditions exist.

The input circuit of the flip-flop includes a pulse steering network 618. An A-l input terminal is connected via a diode 620 (used for isolation) to a gating diode 622 which is connected to the base of the l-transistor 606. A trigger input 624 is connected via capaictor 626 to the junction of the diodes 620 and 622. Resistor 628 at the junction of diode 624 and capacitor 626 is connected to V1 as is a resistor 630 connected to the junction of the diodes 620 and 622. The resistor 628 provides a leakage path for the capacitor 626, and resistor 630 and capacitor 626 form a differentiating network. A similar network is provided from the A-t) input terminal with corresponding parts being referenced by the same numerals together with the addition of a prime the trigger input and diode 624 and resistor 628 are common to both the A-0 and the A-l circuits.

In operation, if the A-0 input is at ground and the A-l input is a negative voltage, the gating diode 622' is essentially at zero bias, and the diode 622 is heavily back biased. A positive trigger pulse applied to the T- terminal is passed by the capacitor 626 and the diode 622' to turn off the transistor 606 and set the tlip-op in the l-state. This same trigger pulse finds the diode 622 back biased and is not sufficient to overcome that bias so that there is no effect directly on the 1-transistor 606. With the input voltages reversed so that the A-0 terminal is at negative voltage and the A-l terminal is at a positive voltage, the trigger input is steered through diode 622 to turn off the l-transistor and reset the ipflop to the 0-state.

The A-1 and A-0 inputs are hereinafter briefly referred to as the l-inputs and O-inputs, respectively.

In addition to the inputs noted above, B-t) and B-l inputs are provided in the form of the input terminals 614 and 614. These inputs provide alternative access to control the state of the flip-flop. Generally, a pulse steering gate 618 (or half of one) is used at the B-0 and B-l inputs. Moreover, an input terminal 630 is connected directly to the collector of the transistor 606 (the l-output); thereby, when the flip-flop is in the 0-state with O-transistor 606' conducting, a positive pulse applied to the terminal 630 is effective to reverse the state of the flip-flop to place it in the l-state. Thus, an output of the flip-Hop may also be used as an input terminal. A similar input terminal (not shown) connected to the collector of the O-transistor 606' (the 0-output) is used to reset the flip-flop to the 0-state.

To summarize, the flip-flop is reset to the O-state by a ground signal at the R-input, B-l input, or 0-output or at the l-input together with a trigger pulse at the T- input. It is set to the l-state by a ground signal at the B-O input, the 1-output, or at the O-input together with a trigger pulse. When reset, the land O-outputs are respectively at low and high voltage levels; when set, the 1- and O-outputs are respectively high and low.

The operation of the pulse steering gate 618 is such that the application of ground potential to the A-0 or A-l terminals does not affect the state of the flip-flop in the absence of a trigger pulse applied to the T-terminal. That is, the A-tl and A-1 input terminals are driven from the collector of a NOR transistor (FIG. 6 or 7), and the small voltage drops in the emitter-collecto-r path of such a transistor in addition to the voltage drops in the diodes 620 and 622 are such that the conducting transistor 606 remains forward biased. The decoup-ling diode 620' is effective to isolate the transistor of the driving circuit from the effect of a trigger pulse passed by the capacitor 626'; moreover, this diode 620 prevents any loading by the driving circuit of the trigger pulse passed by the capacitor 626. Accordingly, the pulse Steering gate 618 is effective to control the state of the flip-flop in accordance with the voltages applied to the A-0 and A-l input terminals with rapid operation thereof.

The flip-flop of FIG. 8 may be converted to a binary counter stage by connecting the 0- and 1-output terminals to the A0 and A-l input terminals, respectively. Thereby, trigger pulses are effective t0 turn off the conducting transistor and reverse the state of the flip-flop, and successive such trigger pulses are thereby counted by the flip-flop in binary fashion. By cascading such counter stages (with one connected to the T-input of the next), various binary counters may be provided. Also, only one of the output terminals (say, the O-terminal) may be connected to the associated input terminal (A-0); in

that case, after having been reset, the next trigger pulse sets the flip-flop.

The R-input of the ip-flop may be connected directly to ground to automatically reset the flip-flop in the absence of a trigger pulse. With the O-input also at ground, a trigger pulse reverses the state of the flip-Hop momentarily during its duration. Thereby, the ip-fiop may be used as a pulse-forming circuit.

The binary signals are generally in the form of voltage levels. A high (ground) level represents "1 and a low, negative level represents "0"; these signals are also used generally to represent, respectively, a command and the inverse form of the command. The inverse form of a signal identifier is represented by the addition of a prime thereafter. Any inverted signal that is present is a negative voltage level. Any signal is converted to its inverted form, and vice versa, by a gate or an inverter.

These particular circuits and signal forms are illustrated as a preferred form of this invention; however, other known circuits, logic types, and signals may be utilized with features of this invention.

Various forms of magnetic recording may be used, as well as various forms of read-write heads and amplifiers; suitable forms are known in the art. This invention is not limited in its scope to magnetic drum storage; other memories may be used. For example, a cyclic recirculating delay line storage may be used with this invention.

Consoles and data colIectors The consoles and data collectors are similarly constructed and operate similarly (except as otherwise noted).

In FIG. 2A, three consoles 56, 57, land 58 of the eight consoles associated with #1 data collector 52 are shown. These consoles 56-58 are generally the same in construction (and the same as the other consoles of the system); #1 console 56 includes a plurality of switches 80-88 each including two contact 90 and 92. Each of the contacts 92 of these switches is connected to a line to receive an enable-console (ground) signal which for #1 console is represented as EC-l. The other switch contact 90 is connected to the anode of a diode 94, the cathode of which is connected as an output line from the console representing SIC-1 for switch 80 (the inverse signal identifier is used for consistency with the remainder of the system; that is, ground voltage may be assumed to represent 0," and a negative voltage, 1"). In a simillar fashion, switch 82 is connected to a diode to the output line SIC-2, iand switch 84 is connected to a diode to the output line SIC-20. Seventeen other such switches and yassociated diodes are connected to lines SIC-3 to -20 as indicated by the dotted lines. In addition, switches 86 and `88 have their upper contacts connected via diodes to H and L selector lines, respectively. Additional switches, diodes, and other selector lines (not shown) as required by the user are connected in a similar fashion; these switches, etc. are not illustrated for simplicity.

The switches -88 are closed or left open under manual control of an operator via any suitable mechanism. An appropriate f'orm of switch mechanism is described in the copending application of Sinn, Data Selection System, Ser. No. 113,690, filed May 31,1961.

In DC #1 corresponding output lines of consoles 56- 58 are connected together; that is, the SIC-1 lines are connected together, the SIC-2 lines are connected t0- gether, etc., the H lines are connected together, the L lines are connected together, etc.

In a similar fashion, in DC #2 and associated consoles 53, the SIC' lines and the category lines H and L are similarly connected together to common lines, and t-hese common lines are connected to the associated lines from DC-L DC-S and yassociated consoles are constructed in a similar fashion with similarly connected output lines. Thus, the SIC'-1 lines of all of the data collectors are connected together to a common SIC-1 line 95, the SIC-2 lines of all the data collectors are connected together to a common SIC2 line 96, and so on for each of the SIC' lines; similarly, the category lines H of each of the data collectors are connected together to a common H selector line 97, the L lines are connected together to a common L selector line 98, and so on for each of the other category selectors.

In FIG. 2B the sequency control, or commutator, for supplying the enable signals EC-l through EC-8 is shown; it includes a shift register 99 that comprises eight flip-flops 100, 102, 108. The l-output and O-output of each flip-op is connected to the -input and l-input, respectively, of the succeeding flip-flop. The T-input to each ip-tlop receives an inverted command pulse, Advance, which pulse (on the trailing edge thereof, when it returns to ground) enables the input of the flip-flop to accept the output levels of the preceding ip-op. Thereby, the state of each ip-op is shifted to the succeeding one.

The Advance signal is received by the data collector at an Advance-in line 301, inverted in an inverter 110, and supplied as Advance' to the T-inputs of flip-flops 100, 102, 108. The output of inverter 110 is also inverted by inverter 112 to supply an Advance-out line with the Advance signal for the succeeding data collector. The first flip-liep 100 of the shift register 99 is set to the l-state by an enable-console signal (EC) which is vreceived at an EC-In terminal and the Advance signal. This EC signal is supplied by a switch 114 when in the upper position (as viewed in FIG. 2B) to the G-input of the first flip-flop 100 and via inverter 116 to the l-input of FF-100. When the switch 114 is in the lower position (as viewed in FIG. 2B), a negative potential is provided in place of the EC signal. This negative potential represents the EC signal and effectively resets FF-100 to the O-state.

The land O-outputs of FF-100 are used as EC-l and EC1 signals, the corresponding outputs of F12-102 are used as EC-2 and EC-2 signals, and so on. The EC-8 signal from FF-108 is also used as an EC-Out signal which is supplied directly to the EC-In terminal of the succeeding data collector 53 if one is used. This connection effectively cascades the shift registers of successive data collectors.

Three gates 118, 120, and 122 receive the eight EC signals from the communtator flip-flops in groups of three, with the third input of gate 122 being a command signal Zero-In (in inverted form) when a second data collector 53 is connected thereto. The outputs of the gates 118, 120, 122 are inverted and supplied to another gate 124, the output of which is supplied, via a switch 126 in the lower position thereof, as an input to the l-output of FIJ-100.

When the switch 126 is in the upper position (as shown for data collector 53 in the lower right corner of FIG. 2B), the Zero signal is supplied to an inverter 128, the output of which is connected to the Zero0ut terminal. Thereby, a Zero' signal is supplied to the preceding data collector in the sequence.

The gate 124 supplies a high level signal when all of the EC inputs to the gates 118, 120, 122 are low, and the Zero'-In terminal is also low (or open-circuited). This high signal at the output of gate 124 is effective to set FF-100 to a l-state. Thus, the gates 118-124 are effective to recognize the condition of all of the commutator flip-flops 100, 102, 108 being in the O-state, and to set FF-100 to the l-state under those circumstances. Where a plurality of data collectors are connected in a string, the Zero' signal from any one of them represents that all of its flip-flop stages are in the O-state and that those of the succeeding data collectors are likewise in 0- states. Thus, only when the shift register stages of all 8 the data collectors are in the O-state is the first stage FF- 100 set to the 1state.

In operation, initially one of the flip-flops of the commutator is in the l-state (if all of them are in the 0-state, gate 124 supplies a O-signal to set ip-flop 100 to the 1- state). With each Advance pulse that is supplied (at the trailing edge thereof when it goes high) this l-state is successively transferred to the succeeding flip-Hop of the commutator. Thereby, during eight successive Advance' pulses the EC signal appears at the EC-l to EC-8 lines successively. When the first flip-hop 100 is in the l-state, console #1 (FIG. 2A) is enabled by the EC-l signal supplied to the switch contacts 92. This enable signal is passed by all of the switches 80-88 that are closed and via the associated diodes 94 to the associated output lines. Thereby, the data collector output lines SIC-1 to -20 contain a combination of high signals representing the particular stock selected by the operator. In addition, one of the category selectors H or L contains a high voltage signal. This combination of request signals at the output of the data collector is handled as a request message to obtain the pertinent information from the slave drum and to transmit it back to the data collector. Upon completion of the reply message, an Advance pulse is supplied to the commutator flip-flops 100, 102, 108 to step the 1state to the second flip-flop 102, at which time a high signal appears on line EC-2 to enable console #2. This operation is repeated successively and upon the l-state being supplied to ip-op 108, console #8 is enabled to perform its request.

In FIG. 2C the reply message portion of DC-l is illustrated. Associated with console #l is a 12-bit register 129 comprising the flip-flops 130, 132, 134, 136 and eight other flip-flops and associated logic that are simply represented as the block 138. Each of the stages is identical and includes, in addition to the flip-flop such as FF- 130, an information line input 140 which is connected via an inverter 142 to the O-input of the associated ipflop and via inverter 144 to the 1input of the associated flip-flop 130. The Advance signal (from inverter and the EC1 signal are gated together in gate 146 and applied to the T-inputs of all of the register flip-flops -138. The outputs of the flip-flops are derived from the O-output thereof via individual isolating inverters 148. In console #l the outputs of inverters 148 are decoded to decimal form and manifested by a suitable display device; and appropriate arrangement therefor is described in the copending application of Sinn, Data Storage Systern, Ser. No. 102,882, filed April 13, 1961.

A second 12bit register 149 which is generally the same as the console-l register is represented in FIG. 2C by only the first flip-flop stage 150 thereof. A gate 152 receives the Advance and EC2 signals and provides its output to the Tinputs of the second register 149. The second register flip-tiops 150, etc. receive their inputs via the inverters 142 and 144, in the manner described above, when the console #2 is enabled. In a similar fashion, separate 12-bit registers are provided for each of the consoles; only the tirst stage 154 of console #8 register 153 is illustrated in FIG. 2C. The register 153 receives the information inputs appearing on the information lines passed via the inverters 142 and 144 when the EC'-8 signal and the Advance' signal pass through gate 156 to trigger the flip-flops 154, etc.

Each of the other data collectors has its information registers constructed in the same manner as described for DC-l. The eight l2-bit registers in DC-2 for consoles #9-16 are respectively enabled by the associated signals EC'9 to 16. The Advance signal is also applied to DC-2 from the Advance-Out line (FIG. 2B). The output of each inverter 144 is connected to the associated information input line of DC-2. Each of the twelve information lines is similarly connected via inverters 162 and 164 to the 0- and l-inputs of these register flip-flops in the manner described above for DC-1.

A third data collector, if required, has its information (l2-bit) registers connected to the information lines of DC-2 in the same fashion as those of DC-2 are connected to DC-l, and so on. Thereby, the string of data collectors may be made as long as is desired.

In operation, after the first console has sent its request in the form of SIC signals and a category signal, the EC-l signal continues to be high until twelve bits of information are supplied to the lines 140 and the Advance pulse is received. At the leading edge of the Ad- Vance' pulse the gate 146 supplies a pulse to the T-inputs of the register flip-flops 130-138 for console #l to pass the twelve bits of information to the associated Hip-flops. Since all of the other EC signals are low at that time, none of the registers of the other consoles receive the information bits. After the information is registered, the trailing edge of the Advance pulse is effective in the sequencing shift register 99 (FIG. 2B) to step the l-state to FF-102 so that EC-2 is available as a high enabling signal, and the EC-l line together with the other EC lines are low. The request of console #2 set up on the SIC and category selector switches thereof is then processed in a similar fashion. At the next Advance pulse, the twelve information bits that are received on the lines 140 are passed into the 12Jbit register flip-flop associated with console #2 under control of EC-2, and the sequencer 99 is stepped to obtain EC-3. This operation continues successively with each console in order, having its request processed and the requested information returned to the associated 12-bit information register. After the eighth console has had its request filled (where only a single data collector is used), the sequencer logic sets FF-100 to provide EC-l, and the cycle is repeated.

The connection of DC-2 to DC-l involves the connection orf the Advance line thereof to the Advance line in DC-1; and the connection of each information line 160 in DC-2 to the output of the inverter 144 associated with the corresponding information line in DC-l. A common ground connection in the first data collector is connected to that of the second. In addition, the EC- ()ut line at FF-108 of DC1 is connected to the EC-In terminal of DC-2; and the switch 114 in DC-2 is connected to the upper position to receive signals from its EC-In terminal. Also, the switch 126 in DC-2 is connected to the upper position to supply the outputs of its gate 124 via switch 126 and inverter 128 and the Zero- Out terminal of DC #2 to the Zero'-In terminal of DC #1. These connections are shown in the lower right hand corner of FIG. 2B.

In operation, with the two data collectors 52 and 53 connected together, a l6-part commutation cycle is provided; that is, upon completion of the S-part cycle in the commutator of DC-l, the 1state is transferred via the EC-Out terminal to the EC-In terminal of DC-SS. From there via switch 114, the l-state is transferred to the first Hip-flop of the commutator in DC-53, which provides the IEC-9 signal (corresponding to the EC-1 signal in DC #2), and so on. Upon completion of the cycle in DC #2, its logic corresponding to gates 118-124 generates a Zero signal in DC-2, which signal is passed by the switch 126 and inverter 128 as a Zero-Out signal, which `becomes the Zero'-In signal of DC-l. Consequently, the gates 118-124 of DC-1 generate a Zero signal which is passed by switch 126 to generate the 1state in FF-100 to start a new cycle with console #1 in the enabled condition.

In a similar fashion, additional data collectors may be cascadcd as desired. The data collectors are all constructed in the same fashion so that they may be used interchangeably. When a data collector is connected as the first data collector, its switches 114 and 126 are in the down position as shown in FIG. 2B; for succeeding data collectors, the switches 114 and 126 are in the up position, also as shown in FIG. 2B.

This logical configuration of gates 118, 120, 122, and

124 is used to avoid a difiiculty associated with shift registers. Namely, where the shift register is used to carry a single l-bit that is recirculated in the shift register, that bit may be lost due to some momentary malfunction of the hardware or spurious transient condition, or that bit might be joined by an extra spurious bit generated by noise or malfunction. This problem s resolved by the logic of gates 118, 124 recognizing the condition of all of the register stages being in the O-state to initiate the entry of a bit in the rst stage of the shift register. Thereby, it is assured that a bit is always present in the shift register since its loss is only for the period involved in recognition of the condition and generation of a new bit.

If an extra bit is spuriously generated, this condition exists only for the period involved in shifting that bit out of the register. That is, a new bit is not generated until both of the existing bits have been generated out. Thus, there may exist a short transient period when two shift register stages may contain a l-state; during this period, two consoles may be enabled at the same time which would result in a garbled operation for an enabled console, but this condition lasts only for the cycle time of the commutator which at most is only of the order of a fraction of a second and not likely to be more than a second or so. Accordingly, the spurious condition is essentially unnoticed by the operator.

Dafa terminus In FIG. 3A the portion of the data terminus which receives the request message lines is illustrated. A first set of request message gates 200 respectively receive the four SIC lines SIC-1 to SIC4; these gates 200 also receive a timing pulse Y'-4. The neXt set of four gates 202 (shown as a block) receive the SICS to SICLS lines, respectively, together with a timing signal Y-5. In a similar fashion, the four gates 204 respectively receive SIC-9 to SIC-12 together with Y-6; the four gates 206 respectively receive SIC'-13 to SIC-16 together with Y-7; and the four gates 208 respectively receive SIC-17 to SICLZO together with YLS.

Another four request-message gates 210 receive Y-1; and the first two of these gates receive a negative voltage level, and the other two respectively receive the H and L selector signals. The next four selector request gates 212 receive Y'-2, and these four gates respectively receive selector signals corresponding to Last, Volume, Trades, and Time. The next four request gates 214 receive Y'-3, and, in addition, they respectively receive the Bid, Ask, Earnings, and Close selector signals.

The output of each first gate of the groups 210, 212, and 214 is connected to buffer 216; the outputs of the second gates of these groups are supplied to the buffer 218; the outputs of the third gates of these groups, to the buffer 220; the outputs of the fourth gates of these groups, to the buffer 222. In a similar fashion, the gates 200-208 are connected with their outputs, respectively, to the four `buffers 216-222. The outputs of the buffers 216, 218, 220, and 222 are respectively connected to gates 224, 226, 228, and 230 together with timing pulses X1 to X'-4, respectively.

In operation, the Y' timing pulses last for four successive X' pulses; that is, `for the period of the X-1 through X'-4 pulses, as indicated by the idealized graph in FIG. 3A. When Y-1 occurs, the gates 210 are enabled to pass their input signals via the buffers 216 to 222 to gates 224 to 230, respectively. Initially, X'1 and the low voltage level supplied thereto produce a high output from gate 224 representing a l-bit; then XL2 enables gate 226 with the similar low voltage applied thereto to supply another 1-bit output; X3 enables gate 228 to produce the H' signal as an output; and X-4 enables gate 230 to supply the L' signal. These four signals are supplied via a level setting circuit 231 to Tx 47; the level setting circuit may tbe an adapting amplifier that converts the gate output signals to levels suitable for inputs to the transmitter. The next cycle of X signals occurs during Y'-2 when gates 212 are enabled, during which time the next four selector signals are passed through the output gates 224-230; and the next cycle of X pulses successively enables passage of the next four selector signals supplied to gates 214 through to the output line and Tx 47. During the next cycle of Y-4, the SIC-1 to -4 are successively produced as outputs of gates 224-230, respectively, by the X'-1 to -4 signals. This cycle is repeated in a similar fashion during the Y'-5, Y'-6, Y'-7, and Y-8 timing periods, during the last of which the SIC-17 to -20 signals are successively produced as outputs of gates 224-230, respectively.

Thus, the data terminus unit of FIG. 3A is effective to receive the SIC and selector signals in parallel from the data collector and to convert the parallel series of signals to a train of signals in serial form preceded by two l-bit index signals represented by high voltage levels. This serial train of signals is the request message.

In FIG. 3B the remainder of the data terminus unit 50 is illustrated; and in the lower portion thereof, the sequencer 233 for developing the X and Y' signals is illustrated. This sequencer includes a 4-stage X-shift register made up of four ip-flops 232-238 connected in cascade with the land -outputs of the first FF-236 respectively connected to the 0- and l-inputs of the second ITF-238; the 1- and O-outputs of the second FF-234 respectively connected to the 1- and O-inputs of the third FF-236 (the third F13-236 being connected in a relatively inverted form); the 0- and 1outputs of the third FF-236 being connected to the 0- and l-inputs of the fourth FF-238; and the land O-outputs of the fourth FF-238 being connected to the 0- and l-inputs of the first FF-232 for recirculation. These flip-flops 232-238 are reset at the same time via line 240. Shift pulses are supplied in the form of SA' signals via inverter 242 to the T-inputs of the shift register flip-flops.

In operation, the shift register flip-flops 232-238 are initially reset by a high signal on the line 240. When so reset, the line X-3 is a low signal (being taken from the l-output of FF-236), and lines X-1, X'-2, and X-4 are all high. When the next shift pulse SA is applied to the T-inputs, the l-state is shifted to FF-238 so that line X-4 is low, and the other outputs are all high. The succeeding shift pulse SA causes the 1state to be recirculated so that the low output is transferred to line X'-1; the third SA shifts the low output to line X-2; and the fourth SA shifts the low output to line X-3, and so on cyclically.

The other part of the sequencer includes the shift register of ip-llop stages 244, 246, 248 (respectively represented as FF-S, FF-, FF-l), and of seven similar stages in a block 250 (representing FF-2 to -8). FF-S is connected in an inverted configuration (similar to ip-tlop 236 described above), and has its 0- and 1outputs respectively connected to the 0- and l-inputs of FIT-246. The land -outputs of FF-246 are connected to the 0- and l-inputs of FF-248, and so on with flip-flops 248- 250 connected in the latter fashion. The Y-0 to Y'-8 outputs are taken from the O-outputs of FF-I] to -8. FF-244 to -250 are also reset from the line 240. The T-inputs of all of these tiip-ops receive signals via inverter 252 from the l-output of flip-flops 238. The 0- input of ip-llop 244 is connected to ground, and the 1- input thereof is left unconnected.

In operation, the reset signal initially resets all of flipflops 244-250. Thereafter, upon recirculation in the X-register, FF-238 is reset to the O-state and its l-output changes from a ground voltage to a low voltage which is inverted by inverter 252 to supply a ground trigger voltage to FF-244 to -2S0. FF-246 is set to the l-state due to the ground and low voltages then appearing on its 0- and 1-inputs, respectively (from reset F13-244); and

flip-flop 244 is also set to the l-state due to ground on its O-input. Upon completion of the next complete cycle of the X ip-ops 232-238, another trigger pulse is passed via inverter 252 to shift the l-state from FF-246 to FF- 248. This process is repeated for each cycle in the X flipflops, and, for nine such full cycles, the l-state is successively transferred from FF-246 through the last flip-flop of block 250. The initial two steps in 12F-236 and -238 are used to start the sequence by transferring the l-state into FF-246, which 1state is effectively established by the inverted position of reset FF-244. In other words, two SA pulse times after reset of all the sequencer ipops 232-238 and 244-250, FF-246 is set to the l-state to develop the Y'-0 signal. After the next four SA pulses, the X ip-op cycle is again completed to develop Y1, and so on. When Y'-1 is developd, the gating operation of the next request message is initiated as described above in connection with FIG. 3A.

In the upper part of FIG. 3B the portion of the data terminus that is effective to receive and process the reply message from Rx 48 is illustrated. The signals from Rx 48 come in at a 1 kilocycle rate and are supplied to a shaper 260 which is an appropriate form of amplifier and signal-forming and level-setting circuit to adapt the signals from Rx 48 to the form needed for the circuitry of the data terminus. The output signals of the shaper 260 are a high, or ground, voltage level representing l and a low voltage level representing 0.

These voltage levels are supplied directly (and via an inverter 262) to the O-input (and the l-input) of the rst flip-flop 264 of l2bit reply message shift register 266. FF-2 to -10 of shift register 266 are illustrated simply by a block 263; FF-ll and -12 thereof are represented by the blocks 270 and 272. The flip-flops of the shift register 266 are connected in the manner described above, and the stages are generally the same except for features hereinafter noted. The information outputs from the shift register 266 are taken in parallel from the 1outputs of the individual flip-flop stages and fed via inverters 274 to the lines INF-1 to 12, respectively, which are the reply message input lines to the data collector (FIG. 2C).

The information pulse from the shaper 260 is also supplied to a flip-flop 280 which has its R- and O-inputs grounded so that it functions as a pulse-former. The tl-output of FF-280 is applied to an inverter driver 282 which resets a 5-stage binary counter 284. The trigger input to the counter 284 is from an oscillator supplying pulses at a 32 kilocycle rate. The count of 16 in the binary counter is detected by supplying the l-output of the last stage of counter 284 to the l-input of a pulseformer F12-286, the R- and 0ir|puts of which are grounded. The opposite side of the last stage of the binary counter 284 is supplied to the T-input of another pulse-former FIT-288, the 0- and R-inputs of which are grounded. The O-output of FF-286 is used as a shift pulse signal SA', which s applied to gate 290 and thence to the T-inputs of the twelve stages of shift register 266; SA' is also used as the trigger input of sequencer 233.

The gate 290 is enabled by the O-output of FF-292 (shown as formed by two NOR circuits connected in a regenerative configuration). The set input to the ipflop 292 is the Y-8 signal which is available from the last stage of the sequencer 233 during the last portion of the transmission of the request message. Another set input to FPi-292 is a normally low signal from a four second detector circuit 294 which is described below. Any reply information left in the register 266 is effectively cleared during the transmission of the request rnessage; that is, Y-2 clears FF-l to -5, and Y-3 clears FF-' to 10, and FF-ll and -12 are cleared by the first shift pulses SA supplied thereto.

The binary counter 284 and associated logic function to produce a shift pulse SA' for each count of 16 therein. The synchronization of these SA' pulses representing counts of 16 is by means of the reset of the binary counter 284 each time that an information l-bit pulse is received. That is, the binary counter 284 is reset at the leading edge of an information pulse, and the count of 16 occurs approximately midway in the duration of that informatio-n l-bit pulse (which is b'eing supplied at a 1 kc. rate and of 1 millisecond duration) so that the narrow SA' pulse (the duration of which is the order of microseconds) effectively samples the information pulse at its midway portion. Since the information l-bit pulses occur relatively frequently in any reply message, the binary counter operation effectively synchronizes the reply message register 266 to the dataphone transmission.

The reply message that is transmited is in the form of a 17-bit message, the last twelve bits of which are information and the first five bits of which are index l-bits. When the first five index bits are established in F13-8 through F12-12, gates 296, 298, 300, and 302 recognize FF-8 through -10, and gate 298 receives the 0outputs of FF-ll and -12 together with the SB pulse. The outputs of the gates 296 and 298 are respectively connected to the inverters 300 and 302 which function as a gate since their collectors are tied together (i.e., the common output of inverters 300 and 302 is a low signal only when the respective inputs are all high, which condition represents all five index signals being supplied to gates 296 and 298 together with SB). Thus, when the live index bits lare established in FF-S through -12, a signal is supplied to gate 304 (enabled by the l-output of a flip-flop 306) to supply a reset pulse to the line 240.

The resetting of the sequencer via line 240 initiates the cycle of sequencer 233 in the manner described above. At the same time, the last five bits of the request message continue to be supplied via Rx 48 and shaper 260 to the reply message shift register 266. These next five information bits are effectively counted in the sequencer 233; that is, the receipt of the first of these last five bits in FF-264 is synchronized with a first SA', which is counted by the l-state being shifted into FIT-238 of the sequencer. The next four bits are counted by a complete cycle of the X flip-ops and FF-238 is again in the 1- state when the fifth bit has been established in the shift register 266. The count of the last five information bits is indicated by X4 and Y-0, which signals are supplied to gate 297 together with SB' to reset FIJ-292, which, in turn, closes gate 290 to prevent further shift pulses being supplied to the reply message shift register 266.

After the five index pulses are recognized in FF-S to -12 and the sequencer flip-flops are reset, the first SA' establishes X'-4 which is applied to a gate 308 together with the leoutput of 12F-244. The output of gate 308 is used to reset FF-ll and -12 of reply message shift register 266 (capacitor 309 connected in shunt between gates 298 and 302 stretches the pulse from FF-ll and 12 and ensures a full reset action notwithstanding the resetting of the latter). This reset condition of FF-ll and -12 prevents a second, spurious recognition of the index pulses as the request message is shifted into FF-S (the first bit thereof). This spurious recognition might otherwise arise where the first bit of a reply message is a l-bit, and when it is shifted into FF-S after the true index recognition. Due to the use of binary coded decimal for the signal code representation, a five 1-bit combination does not occur in succession in a valid reply message. In this code representation, only the first or the second bit (most significant digits) of la signal transmission, but not both, can be a 1. The reset action of FF-ll and -12 by X'-4, Y-0 takes place when the first information bit of the reply message is being stepped into FF-S. Accordingly, the gates 296 and 298 receive a five l-bit index combination only when a valid conditions exists.

The four second detector 294 is a circuit which is driven by the positive voltage step appearing at the l-output of FF-292 when the latter is set, eg. by Y-8 upon cornpletion of the transmission of the request message. If

F12-292 is not set again in that four second period by another Y-S, the detector 294 supplies a positive pulse to set FF-292 and to reset F12-306. The latter enables gate 304 to pass a reset signal to line 240. As is noted below, a special reply message is generated under the conditions indicated so that the ve index bits thereof are established in FF-S to -12 to generate the reset signal that is supplied via enabled gate 304 to reset the sequencer 233. Thereby, the sequencer cycle is initiated so that the next Advance pulse is generated (by gate 299), and the next console request can be serviced.

A suitable circuit for detector 294 may include a transistor that is normally biased on to provide the desired positive output signal and that is biased off by the voltage across a charged capacitor that is coupled to the l-output of F13-292. The capacitor is charged by the setting of ITF-292 `and has a four second discharge time constant to a voltage at which the transistor is biased on.

The four second detector 294 is effective to correct any momentary stalling of the control cycle, for example, due to Flr-292 or -306 being in the wrong state when the power is turned on, or due to a reply message not being received to reset the sequencer 233.

Normally, flip-flop 306 is reset by the O-output of FFS (which condition occurs when the reset pulse is supplied via line 240) and `by the trigger pulse output of inverter 252, which occurs on the second SA' after reset. When reset, gate 304 is closed, `and dete-ction of the 5-bit index is blocked effectively. The Y8 signal is used to set FIT-306 to enable the gate 304 when the end -of the request transmission is essentially completed. Thus, F12-306 opens gate 304 only for the first index 'detection so that if an improper reply message is received, the sequencer 233 is not reset. With the generation of the second SA', after the sequencer is reset, X'-1 and Y-1 generate an Advance pulse via gate 298 (PIG. 3B). The Advance pulse is effective to initiate storage of the twelve information signals INF-1 to -12 of the reply message that `are established in reply register 266 in the proper data collector registers via lines 140. This Advance pulse from gate 298 is also effective to step the data collector cornmutator (FIG. 2B), las described above, in order to enable the next console to supply its request message. This request message is thus supplied to the gates 200-214 (FIG. 3A) at the end of the Advance pulse during X'-2 after the previous reply has been sent to the data collector, and after gate 224 has passed the first index bit of the next request message. Thereby, the next consoles request is immediately processed.

Thus, the reply portion of the data terminus is effective to receive the reply information as a serial message from the retriever. The information is established in parallel form and on Advance signal is generated and supplied to the data collectors. Thereby, the data collectors are actuated to store the information for the requesting console `and to enable the next console to send its request.

Retriever In the retriever 42, illustrated in FIG. 4, the request message signals received from the data terminus (FIG. 3A) via Rx 45 are supplied to a Shaper circuit 320 which sets the proper levels and forms the pulses received from the dataphone. The signal output of the shaper 320 is in the form of a ground level for binary 1 and a low voltage for binary 0.

These signals are supplied directly and via an inverter 322 to the 0- and 1inputs of a first flip-flop 324 in a 32- stage message shift register 326. Generally speaking, the thirty-two stages of the shift register 326 are connected in a manner similar to those described above with the 1- and D-outputs of one connected to the 0- and 1-inputs of the next, except for FF-15 and -32 which have their inputs inverted. FF-S to FF-13 are represented by a block 328, FF-17 to FF-20 are represented by block 330, ITF-23 to FF-26, by a block 332, and FF-27 to l5 F13-30, by a block 334. In each of these blocks the flipop stages are connected in the same way as the stages immediately precedent thereto, except as hereinafter noted.

Outputs from FF-l to F12-30 are taken in parallel via gates individually associated with these flip-flops. It will be apparent that the outputs from FF-l to FF-20, respectively, represent the bits SIC-20 to SIC1, and the outputs from FF-21 to F13-30, respectively, represent the selector bits E-H in a manner consistent with the operation of the gates in the data terminus (FIG. 3A). The outputs of FF-l to FF-14 are derived from the l-out puts thereof; the outputs of FF-lS to FF-30 are derived from the -outputs thereof due to the inverting relationship of the inputs of FF-IS; and the outputs.

The message signals from the shaper 320 are also supplied to the J-input of a jam gate 346, the O-input of which is grounded. This gate 346 steers the ground signal at one of its inputs to the corresponding one of its outputs and effectively differentiates the pulse supplied to its J-input. Thus, jam gate 346 supplies a pulse at its O-output which is connected to the base input of an inverter 348 which, in turn, is connected via inverter 350 to the R-input of a -stage binary counter 352. The counter 352 receives pulses from a 32 kc. oscillator in a manner similar to that described for the binary counter 284 in the data terminus (FIG. 3B). The 16-count output of the binary counter is supplied to the J-input of a jam gate 354, the l-input of which is grounded, and the loutput of which is applied to the base input of `an inverter 356, which supplies shift pulses SHA via inverter 358 to the T-inputs of FF-1 to FPi-32.

The inverted output of the binary counter at its fifth stage is applied t0 the I-input of jam gate 360, the l-input of which is grounded, and the l-output of which is connected to the base input of an inverter 362 to supply control pulses SHB' to various portions of the logic.

In operation, when the request message is received from Rx 45, the successive thirty-two bits thereof are established in FF-l to FF-32 under the control of the shift pulses SHA. The first two bits of the request message are index l-bits (as noted above in connection with the development of the request message in FIG. 3A). When these index l-bits are established in FF-31 and FF-32, an index detector gate 364 is enabled by the l-output of FF-31 and the O-output of FF-32 (FF-32 being connected in inverted form). A third input to gate 364 is an Enable-Index signal, which is developed from the 1- output of a reset output flip-flop 366 (gated with SHB' in gate 368 and inverted by inverter 370).

The output of gate 364 is used to reset a shift flip-Hop 372, the 0-output of which is supplied via inverter 374 to a Request line 376 to the slave output 38. The Request' signal on line 376 asks the slave output for access to the slave drum 20, and when the slave output 38 is available, the Select signal is supplied therefrom on line 340. This Select signal is effective, via inverter 342 and line 344, to open the gates 336 and read out the contents of the message shift register 326 in parallel. The Select and Re quest' signals continuethereafter for the time that is required by the slave output to process the request and obtain the requested information, and effectively maintain a coupling between retriever 42 and slave output 38.

For the duration of the Select signal, no further shift pulses SHA' are `developed by the binary counter; 'that is, the 1-Output of reset shift ip-flop 372 is supplied via inverter 378 to maintain the binary counter 352 in a reset condition. Accordingly, any signals that may be supplied from Rx 45 during the time that the Select signal is on are not shifted into FF-l and do not affect the contents of the message shift register 326.

When the requested information has been obtained by the slave output, it supplies an Advance-signal on line 380 and, at about the same time, supplies the twelve information bits to the inputs of six jam gates 382-392;

gate 382 receives INF'-1 and -2 at its respective two inputs, and so on, with gate 392 receiving INF-11 and INF-12 at its respective two inputs. The land 0-outputs of jam gate 392 are respectively connected to the B-0 inputs of FF-15 and 16, and so on, with the land 0- outputs of gate 382 being applied to the B-0 inputs of FF-25 and -26.

When the Advance pulse is received on line 380, it is supplied via inverter 381 to gate 383, which is enabled by still `present Select'. The output of gate 383 is applied to a jam gate 385, the O-input of which is grounded, and the 0-output of which is applied to the base input of inverter 387 which, via inverter 391, supplies a reset signal to line 393. Thus, the Advance signal on line 380 is differentiated in gate 385 to supply a high reset signal on line 393 which is connected to the R-inputs of all the stages of message register 326. Thus, the Advance pulse is effective at its leading edge to reset the shift register 326.

In addition, the Advance pulse is inverted by inverter 394 and supplied to the J-inputs of the jam gates 382-392. Thus, when the Advance pulse terminates, Advance on line 396 goes positive to jam the information signals on the inputs of the gates 382-392 into 12F-26 to 15. Accordingly, the requested information is established in a porti-on of the message register 326 and ready for transmission back to the data terminus 50.

The gated Advance pulse is also supplied, at its leading edge, to set the output flip-flop 366, which supplies an enabling output signal via line 398 to output gate 400, the output of which is supplied by a level-changing circuit 402 to the transmitter 46. When the output gate 400 is initially enabled, the 0-output of reset FF-32 is at a high voltage, and no change takes place at the output of gate 400.

The gated Advance pulse is also supplied at its leading edge to set shift ip-llop 372 so that its l-output is high, and the disabling, resetting signal on the binary counter 352 is removed. Accordingly, upon the next count of 16 in the binary counter 352, a shift pulse SHA is generated which shifts the reset state of ITF-31 into FF-32, where it is effectively inverted and appears on its O-output as a low voltage signal that is passed by enabled output gate 400 as a l-bit to the level changer 402, which supplies it to Tx 46. Successive shift pulses SHA are generated from the binary counter 352 at the transmission rate, and the tirst five bits (originating in FIT-27 to -3l) passed by gate 400 are index l-bits.

The successive shift pulses SHA shift the information out of registers FF-15 to ITF-32, and via gate 400 to Tx 46 for transmission back to the data terminus. Upon completion of this transmission, the message shift register 326 is clear and ready to receive the next request message from Rx 45. When the data terminus receives the full reply message, the sequencer 233 thereof initiates the sending of another request message. Accordingly, the retriever is in proper condition to receive that next message.

When the first bit (an index l-bit) of the next message is supplied to FF-14 of message register 326, the l-output of )FF-14 connected via line 404, to the output ilip-op 366 resets that Hip-flop. The latter provides Enable Index' for gate 364 to detect the arrival of the index bits of the request message in FIT-31 and -32. FF-14 is used to provide the detection of the first bit of the new request message for changing the state of output flip-flop 366 because it is the last ipflop in the register 326 which is not used for the reply message. This insures that the index detector gate 364 remains disabled as long as convenient to prevent any noise signal which may have gotten into the shift register from initiating operation of the control logic. However, if any serious noise does result in a detection by gate 364, it may cause a momentary error in the display, but on the next request cycle within a short period of time, the display is corrected, and to the operator, it may appear only as a momentary flicker.

At the l-input of the shift fiip-op 372, a resistor 410 and capacitor 412 are connected in series with their junction at the input to the Hip-flop. This resistor-capacitor combination is eiective to apply a positive pulse to the Hip-Hop to reset it when the power is first turned on. The reset flip-flop 372 has the effect of resetting the binary counter 352 and also stimulates the sending of Request to the slave output to initiate the operation of the system and the effective coupling of the retriever to the slave ouput.

When the Advance pulse sets the flip-flop 372, the Request signal is terminated, and at about the same time, the slave output operates, as noted below, to step to fill the request of the next retriever.

Another 4-second detector 410 (similar to that 294 of FIG. 3B) is provided in the retriever and is connected to receive the Advance pulses via gate 383 and supply a pulse to buffer inverter 374. Thereby, if an Advance pulse is not received within 4 seconds, the detector 410 initiates the generation of Request' which signal is effective to couple the retriever to the slave output, as is described below.

To summarize, the retriever receives a serial request message from the data terminus and establishes it in parallel in register 326. The index bits are detected, Request' to the slave output is generated, and Select is returned therefrom. When the slave output is ready to return the reply information, it supplies Advance to clear the register 326 and enter the information therein in parallel. The information is then sent out as a serial reply message to the data terminus.

Slave output The control logic of the slave output unit is shown in FIG. 5. In the upper left hand corner of that figure are shown the twenty stock identifier signals SIC-C of the request message and originating with the console. In the lower left hand corner of FIG. 5, a fragmental portion of the drum 20 is shown. An enlarged fragment of the drum 20 is shown in FIG. 9 illustrating the format of the arrangement of the SIC and information signals on the drum.

Five tracks on the drum are provided for the stock identification code; and four bit positions around the drum, which make up a cell, store the twenty SIC signals in those tive tracks, as illustrated in FIG. 9. That is SIC-1 to -5 are stored in the ve tracks in parallel at the first bit position of the cell, SIC-6 to 10, in the second bit position, and so on. In another track on the drum a signal is stored at each bit position, and this signal, when read back by its associated recording head and amplifier 430 (FIG. is used as a P-l pulse (FIG. 10). In an adjacent track an indexing signal I-l is stored at the first bit position of each cell, and this track is read by a recording head and amplifier 432 to provide the I-1 signal (FIG. l0) which occurs synchronously with the associated P-l. In a third track a quadrant signal Q is stored at each of four spaced quadrant points around the drum. At the corresponding P-l and I-1 bit positions of the drum, the quadrant signal is read by a head 434 to provide the Q-l signal (FIG. From the P-l timing signals, additional P-2 and P-3 timing signals occurring at substantially equally spaced intervals within a bit time interval are derived; for example, the P-2 and P-3 signals may be derived by applying the P-l signal to two cascaded delay lines of approximately equal delay and deriving the P-2 and P-3 signals at the outputs of the respective delay lines. The G-1 to G-4 signal levels (FIG. 10) are produced on separate lines and occur at intervals corresponding to the l-4 bit positions of each cell. They may be derived by triggering a 2-stage binary counter by successive P-1 pulses (after the stages of the counter are reset by I-l pulses) and using a decoder to gate out G-l to G-4 on separate lines during the time intervals when the respective counts are registered.

The gating signals G-l to G-4 are respectively applied to four groups of gates 440, 442, 444, and 446 (FIG. 5), which gates also receive the SIC-C signals. These gates 440-446 are similarly constructed, and only the details of gates 440 are shown. Gates 440 comprise five individual gates that respectively receive the SIC-1 to SlC'-5 signals. Bach of these gates is gated by the G-l signal applied thereto via an inverter. The outputs of the ve gates 440 are respectively connected to five lines 448-456 and thereby to five gates 458-466, respectively. The signals supplied from gates 440 to lines 448-456 are SIC-C-l to -6 due to the inversion taking place in those gates. The gates 442 supply SIC-C-6 to -10 to lines 448-456, respectively, during interval G-2, and so on. The other inputs to the gates 458-466 are derived from the SIC bin 32 on the drum by heads and ampliers 26 and supplied to lines 468, 470, 472, 474, 476 and via inverters to lines 468', 470', 472', 474', 476', respectively. During the gating interval G-l, SIC-D-I to -S are applied to gates 458-466 (via lines 468476, respectively); during gating interval G-Z, SIC'D-6 to 10; during gating interval G-3, SIC'-D-11 to 15; and during G-4, SIC-D16 to 20.

The lines 448-456 are also respectively connected to gates 478-466, respectively, via separate inverters 488; thereby, the SIC-C signals are supplied to the gates 478- 486. The other inputs to the gates 478-486 are respectively the SIC-D signals from the lines 46S-476.

The outputs of the gates 458-466 and 478-486 are all connected via a buffer 490 and a gate 492 (enabled by P'-2) to the l-output of a coincidence flip-flop 494 to set FF-494 with a ground signal (the 1output acting as an input terminal as described in detail in connection with the circuit configurations).

In operation, the logic established by the gates 458-466 and 478-486 is such that if there is coincidence, at least one of the inputs to each of those gates is high, and the outputs thereof are all low, so that a low signal is applied to the 1output of FF-494, and it remains reset. However, if there is anti-coincidence in at least one of the five pairs of SIC-C and SIC-D signals, at least one of the ten pairs of signals applied to the ten gates 458-466 and 478-486 is low, and the output of the associated gate is high. Accordingly, the signal applied to the 1output of coincidence flip-flop 494 is also high to set that ip-iiop.

FF-494 is reset at the beginning of a cell of SIC signals by the I-1 pulse applied to the R input thereof (with the 1input grounded), so that if FF-494 is still reset at the end of that cell, then coincidence is indicated.

Thus, if coincidence is detected between the console request signals SIC-C and the drum signals SIC-D over an entire cell, the next index signal I-1 finds IFF-494 still reset, and its ground signal at the O-output is effective to set FF-496 so that the line 498 at the (l-output thereof becomes low. The line 498 is connected to a gate 500 of a read register 502, and also to two similar read registers 504 and 506. These registers are constructed in the same fashion so that only the register 502 need be described in detail.

The other input to the gate 500 is the P-3 timing pulse via an inverter 508. The output of the gate 500 is applied to the T-inputs of the four ip-ops of register 502 connected as a shift register. The outputs of these four iiipflops are taken at the 1outputs thereof in parallel via separate inverters 510 to provide the INF-1 to -4 signals. The outputs of the read register 504 are the INF-5 to -8 signals, and those from register 506 are the INF'-9 to -12 signals.

The inputs to the read registers 502-506 are derived from the category bins 34, 36, etc. on the drum 20. By way of illustration, the three tracks comprising the High bin 36 are read by individual read-write heads and amplifiers 30, the outputs of which are supplied to three read-out gates shown as a group 512. The other inputs to these gates 512 is the H selector signal derived from 

1. A DATA RETRIEVAL SYSTEM WHICH COMPRISES (A) A CYCLIC MEMORY FOR STORING DATA, (B) DISPLAY UNITS EACH INCLUDING MEANS FOR PRODUCING REQUEST SIGNALS, MEANS FOR REEIVING REPLIES THERETO AND MEANS FOR DISPLAYING SAID REPLIES, (C) A PLURALITY OF SAID DISPLAY UNITS CONNECTED HAVING A PLURALITY OF SAID DISPLAY UNITS CONNECTED THERETO, (D) A PLURALITY OF DATA RETRIEVING MEANS, (E) A PLURALITY OF COMMUNICATION MEANS CONNECTING RESPECTIVE DATA COLLECTOR-TERMINUS MEANS AND DATA RETRIEVING MEANS FOR TRANSMISSION IN BOTH DIRECTIONS THEREBETWEEN, (F) EACH DATA COLLECTOR-TERMINUS MEANS INCLUDING MEANS FOR RECEIVING REQUEST SIGNALS FROM SAID DISPLAY UNITS AND MEANS FOR TRANSMITTING CORRESPONDING REQUEST MESSAGES TO THE RESPECTIVE DATA RETRIEVING MEANS, (G) EACH DATA RETRIEVING MEANS INCLUDING MEANS FOR STORING REQUEST MESSAGES RECEIVED THREAT, (H) MEMORY OUTPUT MEANS HAVING SAID PLURALITY OF DATA RETRIEVING MEANS CONNECTED THERETO, (I) SAID MEMORY OUTPUT MEANS INCLUDING MEANS RESPONSIVE TO REQUEST MESSAGES FOR SAID DATA RETRIEVING MEANS FOR OBTAINING CORRESPONDING REPLAY DATA FROM SAID MEMORY AND MEANS FOR SUPPLYING THE REPLY DATA TO THE REQUESTING DATA RETRIEVING MEANS, (J) SEQUENCING MEANS RESPONSIVE TO THE SUPPLYING OF REPLY DATA TO ONE DATA RETRIEVING MEANS FOR ENABLING THE NEXT DATA RETRIEVING MEANS TO SUPPLY A REQUEST MESSAGE TO THE MEMORY OUTPUT MEANS AND RECEIVE REPLY DATA THEREFROM, (K) EACH DATA RETRIEVING MEANS INCLUDING MEANS FOR STORING REPLY DATA AND MEANS FOR TRANSMITTING A CORRESPONDING REPLY MESSAGE TO THE RESPECTIVE DATA COLLECTOR-TERMINUOUS MEANS, (I) MEANS AT EACH DATA COLLECTOR-TERMINUOUS MEANS FOR SUPPLYING REPLY DATA IN A REPLY MESSAGE TO THE REQUESTING DISPLAY UNIT, (M) AND SEQUENCING MEANS FOR ENABLING THE DISPLAY UNITS CONNECTED TO EACH DATA COLLECTOR-TERMINAL MEANS IN SUCCESSION FOR THE TRANSMISSION OF REQUESTS AND RECEIVING REPLIES THERETO. 